This is a proposal from the Department of Biological Sciences of Oakland University (Rochester, MI) for funds to purchase a Philips 4l0LS transmission electron microscope. At present, the department has a Philips, EM200 that is 19 years old. Because of the age of this instrument and the relatively large number of users, the microscope is frequently out of order. As a result of the "down" time due to the scope (which has run as high as 40% in the past few years) investigators have experienced unnecessary losses in productivity. Contributing greatly to this is the difficulty in obtaining spare parts because of the microscope's age and the manufacturer's decreasing inventory of proper replacement parts. Also, certain inherent problems exist within the scope itself. It is cumbersome to use. The camera system is entirely manual. Its resolution is poor and the finer details of subcellular structures cannot be as clearly defined as is needed for "state-of-the-art" work. The lack of a goniometer stage with a plus or minus 60 degree tilt has prevented investigators from exploring cell organelle relationships that are more readily obtainable using this technique with thick sections rather than standard EM methods. The decision to request funding for a Philips 4l0LS was made for several reasons: 1) it is a state-of-the-art microscope designed for the life sciences, 2) the instrument is capable of a broad magnification range, 3) it is easy to operate, 4) has a fully automatic camera system, 5) needs minimal maintenance, 6) is equipped with a goiometer state and 7) is capable of being expanded in future years to include options such as STEM.